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  • 101.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bessidskaia Bylund, Olga
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clément, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shcherbakova, Anna
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Valdes Santurio, Eduardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Search for Higgs boson decays into pairs of light (pseudo)scalar particles in the gamma gamma jj final state in pp collisions at root s=13 TeV with the ATLAS detector2018Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 782, s. 750-767Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This Letter presents a search for exotic decays of the Higgs boson to a pair of new (pseudo) scalar particles, H -> aa, where the a particle has a mass in the range 20-60 GeV, and where one of the a bosons decays into a pair of photons and the other to a pair of gluons. The search is performed in event samples enhanced in vector-boson fusion Higgs boson production by requiring two jets with large invariant mass in addition to the Higgs boson candidate decay products. The analysis is based on the full dataset of pp collisions at root s = 13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider, corresponding to an integrated luminosity of 36.7 fb(-1). The data are in agreement with the Standard Model predictions and an upper limit at the 95% confidence level is placed on the production cross section times the branching ratio for the decay H -> aa -> gamma gamma gg. This limit ranges from 3.1 pb to 9.0 pb depending on the mass of the a boson.

  • 102.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clement, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kastanas, Alexandros
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Santurio, E. Valdes
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Constraints on off-shell Higgs boson production and the Higgs boson total width in ZZ -> 4l and ZZ -> 2l2v final states with the ATLAS detector2018Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 786, s. 223-244Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A measurement of off-shell Higgs boson production in the ZZ -> 4l and ZZ -> 2l2v decay channels, where stands for either an electron or a muon, is performed using data from proton-proton collisions at a centre-of-mass energy of root s = 13 TeV. The data were collected by the ATLAS experiment in 2015 and 2016 at the Large Hadron Collider, and they correspond to an integrated luminosity of 36.1 fb(-1). An observed (expected) upper limit on the off-shell Higgs signal strength, defined as the event yield normalised to the Standard Model prediction, of 3.8 (3.4) is obtained at 95% confidence level (CL). Assuming the ratio of the Higgs boson couplings to the Standard Model predictions is independent of the momentum transfer of the Higgs production mechanism considered in the analysis, a combination with the on-shell signal-strength measurements yields an observed (expected) 95% CL upper limit on the Higgs boson total width of 14.4 (15.2) MeV.

  • 103.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clement, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kastanas, Alexandros
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Santurio, E. Valdes
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Observation of electroweak W(+/-)Z boson pair production in association with two jets in pp collisions at root s=13 TeV with the ATLAS detector2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 793, s. 469-492Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An observation of electroweak W(+/-)Z production in association with two jets in proton-proton collisions is presented. The data collected by the ATLAS detector at the Large Hadron Collider in 2015 and 2016 at a centre-of-mass energy of root s = 13 TeV are used, corresponding to an integrated luminosity of 36.1 fb(-1). Events containing three identified leptons, either electrons or muons, and two jets are selected. The electroweak production of W(+/-)Z bosons in association with two jets is measured with an observed significance of 5.3 standard deviations. A fiducial cross-section for electroweak production including interference effects and for a single leptonic decay mode is measured to be sigma(WZjj-EW) = 0.57(-0.13)(+0.14) (stat.) (+0.07)(-0.06) (syst.) fb. Total and differential fiducial cross-sections of the sum of W(+/-)Zjj electroweak and strong productions for several kinematic observables are also measured.

  • 104.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clement, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kastanas, Alexandros
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Valdes Santurio, Eduardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Measurements of gluon-gluon fusion and vector-boson fusion Higgs boson production cross-sections in the H -> WW* -> e nu mu nu decay channel in pp collisions at root s=13 TeV with the ATLAS detector2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 789, s. 508-529Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Higgs boson production cross-sections in proton-proton collisions are measured in the H -> WW*-> e nu mu nu decay channel. The proton-proton collision data were produced at the Large Hadron Collider at a centre-of-mass energy of 13 TeV and recorded by the ATLAS detector in 2015 and 2016, corresponding to an integrated luminosity of 36.1 fb(-1). The product of the H -> WW* branching fraction times the gluon-gluon fusion and vector-boson fusion cross-sections are measured to be 11.4(-1.1)(+1.2)(stat.)(-1.7)(+1.8)(syst.) pb and 0.50(-0.22)(+0.24)(stat.) +/- 0.17(syst.) pb, respectively, in agreement with Standard Model predictions.

  • 105.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clement, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kastanas, Alexandros
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Valdes Santurio, Eduardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Search for heavy charged long-lived particles in proton-proton collisions at root s=13 TeV using an ionisation measurement with the ATLAS detector2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 788, s. 96-116Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This Letter presents a search for heavy charged long-lived particles produced in proton-proton collisions at root s= 13 TeV at the LHC using a data sample corresponding to an integrated luminosity of 36.1 fb(-1) collected by the ATLAS experiment in 2015 and 2016. These particles are expected to travel with a velocity significantly below the speed of light, and therefore have a specific ionisation higher than any high-momentum Standard Model particle of unit charge. The pixel subsystem of the ATLAS detector is used in this search to measure the ionisation energy loss of all reconstructed charged particles which traverse the pixel detector. Results are interpreted assuming the pair production of R-hadrons as composite colourless states of a long-lived gluino and Standard Model partons. No significant deviation from Standard Model background expectations is observed, and lifetime-dependent upper limits on R-hadron production cross-sections and gluino masses are set, assuming the gluino always decays to two quarks and a 100 GeV stable neutralino. R-hadrons with lifetimes above 1.0 ns are excluded at the 95% confidence level, with lower limits on the gluino mass ranging between 1290 GeV and 2060 GeV. In the case of stable R-hadrons, the lower limit on the gluino mass at the 95% confidence level is 1890 GeV.

  • 106.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clement, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Santurio, E. Valdes
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Observation of Higgs boson production in association with a top quark pair at the LHC with the ATLAS detector2018Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 784, s. 173-191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The observation of Higgs boson production in association with a top quark pair (t (t) over barH), based on the analysis of proton-proton collision data at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider, is presented. Using data corresponding to integrated luminosities of up to 79.8 fb(-1), and considering Higgs boson decays into b (b) over bar, WW*, tau(+)tau(-), gamma gamma, and ZZ*, the observed significance is 5.8 standard deviations, compared to an expectation of 4.9 standard deviations. Combined with the t (t) over barH searches using a dataset corresponding to integrated luminosities of 4.5 fb(-1) at 7 TeV and 20.3 fb(-1) at 8 TeV, the observed (expected) significance is 6.3 (5.1) standard deviations. Assuming Standard Model branching fractions, the total t (t) over barH production cross section at 13 TeV is measured to be 670 +/- 90(stat.)(-100)(+110)(syst.) fb, in agreement with the Standard Model prediction.

  • 107.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clement, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Santurio, E. Valdes
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Search for vector-boson resonances decaying to a top quark and bottom quark in the lepton plus jets final state in pp collisions at root s=13 TeV with the ATLAS detector2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 788, s. 347-370Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A search for new charged massive gauge bosons, W', is performed with the ATLAS detector at the LHC. Data were collected in proton-proton collisions at a center-of-mass energy of root s = 13 TeV and correspond to an integrated luminosity of 36.1 fb(-1). This analysis searches for W' bosons in the W'-> t ( b) over bar decay channel in final states with an electron or muon plus jets. The search covers resonance masses between 0.5 and 5.0 TeV and considers right-handed W' bosons. No significant deviation from the Standard Model (SM) expectation is observed and upper limits are set on theW'-> t ( b) over bar cross section times branching ratio and the W' boson effective couplings as a function of the W' boson mass. For right-handed W' bosons with coupling to the SM particles equal to the SM weak coupling constant, masses below 3.15 TeV are excluded at the 95% confidence level. This search is also combined with a previously published ATLAS result for W'-> t ( b) over bar in the fully hadronic final state. Using the combined searches, right-handed W' bosons with masses below 3.25 TeV are excluded at the 95% confidence level.

  • 108.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clement, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Valdes Santurio, Eduardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Correlated long-range mixed-harmonic fluctuations measured in pp, p plus Pb and low-multiplicity Pb plus Pb collisions with the ATLAS detector2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 789, s. 444-471Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Correlations of two flow harmonics v(n) and v(m) via three- and four-particle cumulants are measured in 13 TeV pp, 5.02 TeV p+Pb, and 2.76 TeV peripheral Pb+Pb collisions with the ATLAS detector at the LHC. The goal is to understand the multi-particle nature of the long-range collective phenomenon in these collision systems. The large non-flow background from dijet production present in the standard cumulant method is suppressed using a method of subevent cumulants involving two, three and four subevents separated in pseudorapidity. The results show a negative correlation between v(2) and v(3) and a positive correlation between v(2) and v(4) for all collision systems and over the full multiplicity range. However, the magnitudes of the correlations are found to depend on the event multiplicity, the choice of transverse momentum range and collision system. The relative correlation strength, obtained by normalisation of the cumulants with the < v(n)(2)> from a two-particle correlation analysis, is similar in the three collision systems and depends weakly on the event multiplicity and transverse momentum. These results based on the subevent methods provide strong evidence of a similar long-range multi-particle collectivity in pp, p+Pb and peripheral Pb+Pb collisions.

  • 109.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clement, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Valdes Santurio, Eduardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Measurement of photon-jet transverse momentum correlations in 5.02 TeV Pb + Pb and pp collisions with ATLAS2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 789, s. 167-190Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Jets created in association with a photon can be used as a calibrated probe to study energy loss in the medium created in nuclear collisions. Measurements of the transverse momentum balance between isolated photons and inclusive jets are presented using integrated luminosities of 0.49 nb(-1) of Pb + Pb collision data at root(NN)-N-s = 5.02 TeV and 25 pb(-1) of pp collision data at. root s= 5.02 TeV recorded with the ATLAS detector at the LHC. Photons with transverse momentum 63.1 < p(T)(gamma) < 200 GeV and vertical bar eta(gamma vertical bar) < 2.37 are paired with all jets in the event that have p(T)(jet) > 31.6 GeV and pseudorapidity vertical bar eta(Jet)vertical bar < 2.8. The transverse momentum balance given by the jet-to-photon p(T) ratio, x(j gamma), is measured for pairs with azimuthal opening angle Delta phi > 7 pi/8. Distributions of the per-photon jet yield as a function of x(j gamma), (1/N-gamma)(dN/dx(j gamma)), are corrected for detector effects via a two-dimensional unfolding procedure and reported at the particle level. In pp collisions, the distributions are well described by Monte Carlo event generators. In Pb + Pb collisions, the x(j gamma) distribution is modified from that observed in pp collisions with increasing centrality, consistent with the picture of parton energy loss in the hot nuclear medium. The data are compared with a suite of energy-loss models and calculations.

  • 110.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clement, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Valdes Santurio, Eduardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Searches for exclusive Higgs and Z boson decays into J/psi gamma, psi (2S) gamma, and Upsilon(nS) gamma at root s=13 TeV with the ATLAS detector2018Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 786, s. 134-155Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Searches for the exclusive decays of the Higgs and Z bosons into a J/psi, psi(2S), or Upsilon(nS) (n = 1, 2, 3) meson and a photon are performed with a pp collision data sample corresponding to an integrated luminosity of 36.1 fb(-1) collected at root s = 13 TeV with the ATLAS detector at the CERN Large Hadron Collider. No significant excess of events is observed above the expected backgrounds, and 95% confidence- level upper limits on the branching fractions of the Higgs boson decays to J/psi gamma, psi(2S) gamma and Upsilon(nS) gamma of 3.5 x 10(-4), 2.0 x 10(-3), and (4.9, 5.9, 5.7) x 10(-4), respectively, are obtained assuming Standard Model production. The corresponding 95% confidence-level upper limits for the branching fractions of the Z boson decays are 2.3 x 10(-6), 4.5 x 10(-6) and (2.8, 1.7, 4.8) 10(-6), respectively.

  • 111.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clement, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kastanas, Alexandros
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Valdes Santurio, Eduardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Observation of H -> b(b)over-bar decays and V H production with the ATLAS detector2018Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 786, s. 59-86Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A search for the decay of the Standard Model Higgs boson into a b (b) over bar pair when produced in association with a W or Z boson is performed with the ATLAS detector. The data, corresponding to an integrated luminosity of 79.8 fb(-1) were collected in proton-proton collisions during Run 2 of the Large Hadron Collider at a centre-of-mass energy of 13 TeV. For a Higgs boson mass of 125 GeV, an excess of events over the expected background from other Standard Model processes is found with an observed (expected) significance of 4.9 (4.3) standard deviations. A combination with the results from other searches in Run 1 and in Run 2 for the Higgs boson in the bb decay mode is performed, which yields an observed (expected) significance of 5.4 (5.5) standard deviations, thus providing direct observation of the Higgs boson decay into b-quarks. The ratio of the measured event yield for a Higgs boson decaying into b (b) over bar to the Standard Model expectation is 1.01 +/- 0.12(stat.) (-0.15) (+0.16)(syst.). Additionally, a combination of Run 2 results searching for the Higgs boson produced in association with a vector boson yields an observed (expected) significance of 5.3 (4.8) standard deviations.

  • 112.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clément, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Valdes Santurio, Eduardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Measurement of the nuclear modification factor for inclusive jets in Pb plus Pb collisions at root s(NN)=5.02 TeV with the ATLAS detector2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 790, s. 108-128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Measurements of the yield and nuclear modification factor, R-AA, for inclusive jet production are performed using 0.49 nb(-1) of Pb+Pb data at root s(NN) = 5.02 TeV and 25 pb(-1) of Pb+Pb data at root s = 5.02 TeV with the ATLAS detector at the LHC. Jets are reconstructed with the anti-k(t) algorithm with radius parameter R = 0.4 and are measured over the transverse momentum range of 40-1000 GeV in six rapidity intervals covering vertical bar y vertical bar < 2.8. The magnitude of R-AA increases with increasing jet transverse momentum, reaching a value of approximately 0.6 at 1 TeV in the most central collisions. The magnitude of R-AA also increases towards peripheral collisions. The value of R-AA is independent of rapidity at low jet transverse momenta, but it is observed to decrease with increasing rapidity at high transverse momenta.

  • 113.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clément, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Valdes Santurio, Eduardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Search for Higgs boson decays into a pair of light bosons in the bb mu mu final state in pp collision at root s=13 TeV with the ATLAS detector2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 790, s. 1-21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A search for decays of the Higgs boson into a pair of new spin-zero particles, H -> aa, where the a-bosons decay into a b-quark pair and a muon pair, is presented. The search uses 36.1 fb(-1) of proton-proton collision data at root s = 13 TeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the Standard Model prediction is observed. Upper limits at 95% confidence level are placed on the branching ratio (sigma(H)/sigma(SM)) x B(H -> aa -> bb mu mu), ranging from 1.2 x 10(-4) to 8.4 x 10(-4) in the a-boson mass range of 20-60 GeV. Model-independent limits are set on the visible production cross-section times the branching ratio to the bb mu mu final state for new physics, sigma(vis)(X) x B(X -> bb mu mu), ranging from 0.1 fb to 0.73 fb for m(mu mu) between 18 and 62 GeV.

  • 114.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clément, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kastanas, Alexandros
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Valdes Santurio, Eduardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Study of the hard double-parton scattering contribution to inclusive four-lepton production in pp collisions at root s=8 TeV with the ATLAS detector2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 790, s. 595-614Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The inclusive production of four isolated charged leptons in pp collisions is analysed for the presence of hard double-parton scattering, using 20.2 fb(-1) of data recorded in the ATLAS detector at the LHC at centre-of-mass energy root s = 8 TeV. In the four-lepton invariant-mass range of 80 < m(4l) < 1000 GeV, an artificial neural network is used to enhance the separation between single- and double-parton scattering based on the kinematics of the four leptons in the final state. An upper limit on the fraction of events originating from double-parton scattering is determined at 95% confidence level to be f(DPS) = 0.042, which results in an estimated lower limit on the effective cross section at 95% confidence level of 1.0 mb.

  • 115.
    Bertoli, Gabriele
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Carney, Rebecca M. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clément, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kastanas, Alexandros
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Molander, Simon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Pasuwan, Patrawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Shaikh, Nabila W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strandberg, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ughetto, Michaël
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Valdés Santurio, Eduardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallängen, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Measurement of prompt photon production in root s(NN)=8.16 TeV p Pb collisions with ATLAS2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 796, s. 230-252Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The inclusive production rates of isolated, prompt photons in p Pb collisions at root s(NN) = 8.16 TeV are studied with the ATLAS detector at the Large Hadron Collider using a dataset with an integrated luminosity of 165 nb(-1) recorded in 2016. The cross-section and nuclear modification factor R-p pb are measured as a function of photon transverse energy from 20 GeV to 550 GeV and in three nucleon-nucleon centre-of-mass pseudorapidity regions, (-2.83, -2.02), (-1.84, 0.91), and (1.09, 1.90). The cross-section and R-p pb values are compared with the results of a next-to-leading-order perturbative QCD calculation, with and without nuclear parton distribution function modifications, and with expectations based on a model of the energy loss of partons prior to the hard scattering. The data disfavour a large amount of energy loss and provide new constraints on the parton densities in nuclei.

  • 116. Bi, Huan-Yu
    et al.
    Wu, Xing-Gang
    Ma, Yang
    Ma, Hong-Hao
    Brodsky, Stanley J.
    Mojaza, Matin
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita).
    Degeneracy relations in QCD and the equivalence of two systematic all-orders methods for setting the renormalization scale2015Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 748, s. 13-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Principle of Maximum Conformality (PMC) eliminates QCD renormalization scale-setting uncertainties using fundamental renormalization group methods. The resulting scale-fixed pQCD predictions are independent of the choice of renormalization scheme and show rapid convergence. The coefficients of the scale-fixed couplings are identical to the corresponding conformal series with zero beta-function. Two all-orders methods for systematically implementing the PMC-scale setting procedure for existing high order calculations are discussed in this article. One implementation is based on the PMC-BLM correspondence (PMC-I); the other, more recent, method (PMC-II) uses the R-delta-scheme, a systematic generalization of the minimal subtraction renormalization scheme. Both approaches satisfy all of the principles of the renormalization group and lead to scale-fixed and scheme-independent predictions at each finite order. In this work, we show that PMC-I and PMC-II scale-setting methods are in practice equivalent to each other. We illustrate this equivalence for the four-loop calculations of the annihilation ratio Re+e- and the Higgs partial width Gamma(H -> b (b) over bar). Both methods lead to the same resummed ('conformal') series up to all orders. The small scale differences between the two approaches are reduced as additional renormalization group {beta(i)}-terms in the pQCD expansion are taken into account. We also show that special degeneracy relations, which underly the equivalence of the two PMC approaches and the resulting conformal features of the pQCD series, are in fact general properties of non-Abelian gauge theory.

  • 117. Bomark, N.-E.
    et al.
    Lola, S.
    Osland, P.
    Raklev, A. R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Photon, neutrino and charged particle spectra from R-violating gravitino decays2010Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 686, nr 03-feb, s. 152-161Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study photonic. neutrino and charged particle signatures from slow decays of gravitino dark matter in supersymmetric theories where R-parity is explicitly broken by trilinear operators Photons and (anti-)fermions from loop and tree-level processes give rise to spectra with distinct features, which. if observed, can give crucial input on the possible mass of the gravitino and the magnitude and flavour structure of R-violating operators. Within this framework, we make detailed comparisons of the theoretical predictions to the recent experimental data from PAMELA, ATIC and Fermi LAT.

  • 118.
    de Salas, Pablo Fernández
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Institut de Física Corpuscular (CSIC–Universitat de València), Spain.
    Pastor, S.
    Ternes, C. A.
    Thakore, T.
    Tórtola, M.
    Constraining the invisible neutrino decay with KM3NeT-ORCA2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 789, s. 472-479Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several theories of particle physics beyond the Standard Model consider that neutrinos can decay. In this work we assume that the standard mechanism of neutrino oscillations is altered by the decay of the heaviest neutrino mass state into a sterile neutrino and, depending on the model, a scalar or a Majoron. We study the sensitivity of the forthcoming KM3NeT-ORCA experiment to this scenario and find that it could improve the current bounds coming from oscillation experiments, where three-neutrino oscillations have been considered, by roughly two orders of magnitude. We also study how the presence of this neutrino decay can affect the determination of the atmospheric oscillation parameters sin(2) theta(23) and Delta m(31)(2), as well as the sensitivity to the neutrino mass ordering.

  • 119.
    Di Vecchia, Paolo
    et al.
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita). University of Copenhagen, Denmark.
    Luna, Andrés
    Naculich, Stephen G.
    Russo, Rodolfo
    Veneziano, Gabriele
    White, Chris D.
    A tale of two exponentiations in N=8 supergravity2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 798, artikkel-id 134927Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure of scattering amplitudes in supergravity theories continues to be of interest. Recently, the amplitude for 2 -> 2 scattering in N = 8 supergravity was presented at three-loop order for the first time. The result can be written in terms of an exponentiated one-loop contribution, modulo a remainder function which is free of infrared singularities, but contains leading terms in the high energy Regge limit. We explain the origin of these terms from a well-known, unitarity-restoring exponentiation of the high-energy gravitational S-matrix in impact-parameter space. Furthermore, we predict the existence of similar terms in the remainder function at all higher loop orders. Our results provide a non-trivial cross-check of the recent three-loop calculation, and a necessary consistency constraint for any future calculation at higher loops.

  • 120. Ema, Yohei
    et al.
    Karčiauskas, Mindaugas
    Lebedev, Oleg
    Rusak, Stanislav
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita).
    Zatta, Marco
    Higgs-inflaton mixing and vacuum stability2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 789, s. 373-377Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The quartic and trilinear Higgs field couplings to an additional real scalar are renormalizable, gauge and Lorentz invariant. Thus, on general grounds, one expects such couplings between the Higgs and an inflaton in quantum field theory. We find that the often omitted trilinear interaction is only weakly constrained by cosmology and could stabilize the electroweak vacuum by increasing the Higgs self coupling. The consequent Higgs-inflaton mixing can be as large as order one making a direct inflaton search possible at the LHC.

  • 121.
    Enander, Jonas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Mörtsell, Edvard
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    On the use of black hole binaries as probes of local dark energy properties2010Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 683, nr 1, s. 7-10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Accretion of dark energy onto black holes will take place when dark energy is not a cosmological constant. It has been proposed that the time evolution of the mass of the black holes in binary systems due to dark energy accretion could be detectable by gravitational radiation. This would make it possible to use observations of black hole binaries to measure local dark energy properties, e.g., to determine the sign of 1+w where w is the dark energy equation of state. In this Letter we show that such measurements are unfeasible due to the low accretion rates.

  • 122. Freese, Katherine
    et al.
    Savage, Christopher
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Dark matter collisions with the human body2012Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 717, nr 1-3, s. 25-28Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate the interactions of Weakly Interacting Massive Particles (WIMPs) with nuclei in the human body. We are motivated by the fact that WIMPS are excellent candidates for the dark matter in the Universe. Our estimates use a 70 kg human and a variety of WIMP masses and cross-sections. The contributions from individual elements in the body are presented and it is found that the dominant contribution is from scattering off of oxygen (hydrogen) nuclei for the spin-independent (spin-dependent) interactions. For the case of 60 GeV WIMPs, we find that, of the billions of WIMPs passing through a human body per second, roughly similar to 10 WIMPs hit one of the nuclei in the human body in an average year, if the scattering is at the maximum consistent with current bounds on WIMP interactions. We also study the 10-20 GeV WIMPs with much larger cross-sections that best fit the DAMA, COGENT, and CRESST data sets and find much higher rates: in this case as many as 10(5) WIMPs hit a nucleus in the human body in an average year, corresponding to almost one a minute. Though WIMP interactions are a source of radiation in the body, the annual exposure is negligible compared to that from other natural sources (including radon and cosmic rays), and the WIMP collisions are harmless to humans.

  • 123.
    Gerbino, Martina
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Lattanzi, Massimiliano
    Mena, Olga
    Freese, Katherine
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita). University of Michigan, USA.
    A novel approach to quantifying the sensitivity of current and future cosmological datasets to the neutrino mass ordering through Bayesian hierarchical modeling2017Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 775, s. 239-250Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a novel approach to derive constraints on neutrino masses, as well as on other cosmological parameters, from cosmological data, while taking into account our ignorance of the neutrino mass ordering. We derive constraints from a combination of current as well as future cosmological datasets on the total neutrino mass M-nu and on the mass fractions f(nu),i = m(i)/M-nu (where the index i = 1, 2, 3 indicates the three mass eigenstates) carried by each of the mass eigenstates m(i), after marginalizing over the (unknown) neutrino mass ordering, either normal ordering (NH) or inverted ordering (IH). The bounds on all the cosmological parameters, including those on the total neutrino mass, take therefore into account the uncertainty related to our ignorance of the mass hierarchy that is actually realized in nature. This novel approach is carried out in the framework of Bayesian analysis of a typical hierarchical problem, where the distribution of the parameters of the model depends on further parameters, the hyperparameters. In this context, the choice of the neutrino mass ordering is modeled via the discrete hyperparameter h(type), which we introduce in the usual Markov chain analysis. The preference from cosmological data for either the NH or the IH scenarios is then simply encoded in the posterior distribution of the hyper-parameter itself. Current cosmic microwave background (CMB) measurements assign equal odds to the two hierarchies, and are thus unable to distinguish between them. However, after the addition of baryon acoustic oscillation (BAO) measurements, a weak preference for the normal hierarchical scenario appears, with odds of 4 : 3 from Planck temperature and large-scale polarization in combination with BAO (3 : 2 if small-scale polarization is also included). Concerning next-generation cosmological experiments, forecasts suggest that the combination of upcoming CMB (COrE) and BAO surveys (DESI) may determine the neutrino mass hierarchy at a high statistical significance if the mass is very close to the minimal value allowed by oscillation experiments, as for NH and a fiducial value of M-nu = 0.06 eV there is a 9 : 1 preference of normal versus inverted hierarchy. On the contrary, if the sum of the masses is of the order of 0.1 eV or larger, even future cosmological observations will be inconclusive. The innovative statistical strategy exploited here represents a very simple, efficient and robust tool to study the sensitivity of present and future cosmological data to the neutrino mass hierarchy, and a sound competitor to the standard Bayesian model comparison. The unbiased limit on M-nu we obtain is crucial for ongoing and planned neutrinoless double beta decay searches.

  • 124.
    Gudnason, Sven Bjarke
    et al.
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita). Chinese Academy of Sciences, China.
    Nitta, Muneto
    Effective field theories on solitons of generic shapes2015Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 747, s. 173-177Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A class of effective field theories for moduli or collective coordinates on solitons of generic shapes is constructed. As an illustration, we consider effective field theories living on solitons in the O(4) non-linear sigma model with higher-derivative terms.

  • 125.
    Guigas, R.
    et al.
    Kernforschungszentrum, Universität Karlsruche.
    Blüm, P.
    Kernforschungszentrum, Universität Karlsruche.
    Koch, H.
    Kernforschungszentrum, Universität Karlsruche.
    Meyer, M.
    Kernforschungszentrum, Universität Karlsruche.
    Poth, H.
    Kernforschungszentrum, Universität Karlsruche.
    Raich, U.
    Kernforschungszentrum, Universität Karlsruche.
    Richter, B.
    Kernforschungszentrum, Universität Karlsruche.
    Backenstoss, G.
    Pavlopoulos, P.
    Institute for Physics, University of Basle.
    Tauscher, L.
    Institute for Physics, University of Basle.
    Adiels, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum, Manne Siegbahn-laboratoriet.
    Fransson, Kjell
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum, Manne Siegbahn-laboratoriet.
    Nilsson, A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum, Manne Siegbahn-laboratoriet.
    Suffert, M.
    Centre de recherches nucléaries and Université Louis Pasteur, Strabourg.
    Zioutas, K.
    Dept. of Nuclear Physics, Univerity of Tessaloniki.
    Strong interaction effects in antiprotonic 6Li/7Li atoms1984Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 137, nr 56, s. 323-328Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of strong interaction on the 3 –> 2 X-ray transition in antiprotonic 6Li/7Li atoms have been measured at the low energy -beam at CERN. For the shifts and widths of the levels the values [epsilon]2p = (-230 ï¿œ 72) eV, [Gamma]2p = (443 ï¿œ 210) eV, and [Gamma]3d = (0.130 ï¿œ 0.045) eV for 6Li, and [epsilon]2p = (-336 ï¿œ 60) eV, [Gamma]2p = (456 ï¿œ 190) eV, and [Gamma]3d = (0.210 ï¿œ 0.062) eV for 7Li were found. The data are compared with optical model predictions.

  • 126.
    Hassan, Fawad
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Schmidt-May, Angnis
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    von Strauss, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Proof of consistency of nonlinear massive gravity in the Stuckelberg formulation2012Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 715, nr 4-5, s. 335-339Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We address some recent concerns about the absence of the Boulware-Deser ghost in the Stuckelberg formulation of nonlinear massive gravity. First we provide general arguments for why any ghost analysis in the Stuckelberg formulation has to agree with existing consistency proofs that have been carried out without using Stuckelberg fields. We then demonstrate the absence of the ghost at the completely nonlinear level in the Stuckelberg formulation of the minimal massive gravity action. The constraint that removes the ghost field and the associated secondary constraint that eliminates its conjugate momentum are computed explicitly, confirming the consistency of the theory in the Stuckelberg formulation.

  • 127.
    Hassan, S. F.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Rosen, Rachel A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Exact solution to the "auxiliary extra-dimension" model of massive gravity2011Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 702, nr 1, s. 90-93Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The auxiliary extra-dimension model was proposed in order to provide a geometrical interpretation to modifications of general relativity, in particular to non-linear massive gravity. In this context, the theory was shown to be ghost free to third order in perturbations, in the decoupling limit. In this work, we exactly solve the equation of motion in the extra dimension, to obtain a purely 4-dimensional theory. Using this solution, it is shown that the ghost appears at the fourth order and beyond. We explore potential modifications to address the ghost issue and find that their consistent implementation requires going beyond the present framework.

  • 128.
    Hassan, S. Fawad
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Schmidt-May, Angnis
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    von Strauss, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    On partially massless bimetric gravity2013Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 726, nr 4-5, s. 834-838Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We extend the notion of the Higuchi bound and partial masslessness to ghost-free nonlinear bimetric theories. This can be achieved in a simple way by first considering linear massive spin-2 perturbations around maximally symmetric background solutions, for which the linear gauge symmetry at the Higuchi bound is easily identified. Then, requiring consistency between an appropriate subset of these transformations and the dynamical nature of the backgrounds, fixes all but one parameter in the bimetric interaction potential. This specifies the theory up to the value of the Fierz-Pauli mass and leads to the unique candidate for nonlinear partially massless bimetric theory.

  • 129.
    Hossenfelder, Sabine
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita).
    A possibility to solve the problems with quantizing gravity2013Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 725, nr 4-5, s. 473-476Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is generally believed that quantum gravity is necessary to resolve the known tensions between general relativity and the quantum field theories of the standard model. Since perturbatively quantized gravity is non-renormalizable, the problem how to unify all interactions in a common framework has been open since the 1930s. Here, I propose a possibility to circumvent the known problems with quantizing gravity, as well as the known problems with leaving it unquantized: By changing the prescription for second quantization, a perturbative quantization of gravity is sufficient as an effective theory because matter becomes classical before the perturbative expansion breaks down. This is achieved by considering the vanishing commutator between a field and its conjugated momentum as a symmetry that is broken at low temperatures, and by this generates the quantum phase that we currently live in, while at high temperatures Planck's constant goes to zero.

  • 130.
    Hossenfelder, Sabine
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita).
    A relativistic acoustic metric for planar black holes2016Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 752, s. 13-17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate here that the metric of a planar black hole in asymptotic anti-de Sitter space can, on a slice of dimension 3 + 1, be reproduced as a relativistic acoustic metric. This completes an earlier calculation in which the non-relativistic limit was used, and also serves to obtain a concrete form of the Lagrangian.

  • 131. Jiménez, Jose Beltrán
    et al.
    Koivisto, Tomi S.
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita).
    Spacetimes with vector distortion: Inflation from generalised Weyl geometry2016Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 756, s. 400-404Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spacetime with general linear vector distortion is introduced. Thus, the torsion and the nonmetricity of the affine connection are assumed to be proportional to a vector field (and not its derivatives). The resulting two-parameter family of non-Riemannian geometries generalises the conformal Weyl geometry and some other interesting special cases. Taking into account the leading nonlinear correction to the Einstein-Hilbert action results uniquely in the one-parameter extension of the Starobinsky inflation known as the alpha-attractor. The most general quadratic curvature action introduces, in addition to the canonical vector kinetic term, novel ghost-free vector-tensor interactions.

  • 132. Lowe, David A.
    et al.
    Thorlacius, Larus
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita). University of Iceland, Iceland.
    Black hole complementarity: The inside view2014Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 737, s. 320-324Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Within the framework of black hole complementarity, a proposal is made for an approximate interior effective field theory description. For generic correlators of local operators on generic black hole states, it agrees with the exact exterior description in a region of overlapping validity, up to corrections that are too small to be measured by typical infalling observers.

  • 133.
    Oellers, D.
    et al.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Barion, L.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Barsov, S.
    St. Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia.
    Bechstedt, U.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Benati, P.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Bertelli, S.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Chiladze, D.
    High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia.
    Ciullo, G.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Contalbrigo, M.
    INFN, Sezione di Ferrara, 44100 Ferrara, Italy.
    Dalpiaz, P.F.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Dietrich, J.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Dolfus, N.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Dymov, S.
    Physikalisches Institut II, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
    Engels, R.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Erven, W.
    Jülich Center for Hadron Physics, 52425 Jülich, Germany.
    Garishvili, A.
    High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia.
    Gebel, R.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Goslawski, P.
    Institut für Kernphysik, Universität Münster, 48149 Münster, Germany.
    Grigoryev, K.
    St. Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia.
    Hadamek, H.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Kacharava, A.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Khoukaz, A.
    Institut für Kernphysik, Universität Münster, 48149 Münster, Germany.
    Kulikov, A.
    Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia.
    Langenberg, G.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Lehrach, A.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Lenisa, P.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Lomidze, N.
    High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia.
    Lorentz, B
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Macharashvili, G.
    Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia.
    Maier, R.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Martin, S.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Merzliakov, S.
    Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia.
    Meshkov, I.N.
    Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia.
    Meyer, H.O.
    Physics Department, Indiana University, Bloomington, IN 47405, USA.
    Mielke, M.
    Institut für Kernphysik, Universität Münster, 48149 Münster, Germany.
    Mikirtychiants, M.
    St. Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia.
    Mikirtychiants, S.
    St. Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia.
    Nass, A.
    Physikalisches Institut II, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
    Nekipelov, M.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Nikolaev, N.N.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Nioradze, M.
    High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia.
    d'Orsaneo, G.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Papenbrockj, M.
    Institut für Kernphysik, Universität Münster, 48149 Münster, Germany.
    Prasuhn, D.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Rathmann, F.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Sarkadi, J.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    R. Schleichert, R.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Smirnov, A.
    Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980 Dubna, Russia.
    Seyfarth, H.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Sowinski, J.
    Physics Department, Indiana University, Bloomington, IN 47405, USA.
    Spoelgen, D.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Stancari, G.
    INFN, Sezione di Ferrara, 44100 Ferrara, Italy.
    Stancari, M.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Statera, M.
    Università di Ferrara and INFN, 44100 Ferrara, Italy.
    Steffens, E.
    Physikalisches Institut II, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
    Stein, H.J.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Stockhorst, H.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Straatmann, H.
    Zentralabteilung Technologie, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Ströher, H.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Tabidze, M.
    High Energy Physics Institute, Tbilisi State University, 0186 Tbilisi, Georgia.
    Tagliente, G.
    INFN, Sezione di Bari, 70126 Bari, Italy.
    Thörngren Engblom, Pia
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Trusov, S.
    Institut für Kern- und Hadronenphysik, Forschungszentrum Rossendorf, 01314 Dresden, Germany.
    Vasilyev, A.
    St. Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia.
    Weidemann, Chr.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Welsch, D.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Wieder, P.
    Institut für Kernphysik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Wüstner, P.
    Zentralinstitut für Elektronik, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
    Zupranski, P.
    Department of Nuclear Reactions, Andrzej Soltan, Institute for Nuclear Studies, 00-681 Warsaw, Poland.
    Polarizing a stored proton beam by spin flip?2009Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 674, nr 4-5, s. 269-275Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin-flip cross section in low-energy electron–proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam.

  • 134.
    Ong, Yen Chin
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita). Yangzhou University, China; Shanghai Jiao Tong University, China.
    GUP-corrected black hole thermodynamics and the maximum force conjecture2018Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 785, s. 217-220Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We show that thermodynamics for an asymptotically flat Schwarzschild black hole leads to a force of magnitude c(4)/(2G). This remains true if one considers the simplest form of correction due to the generalized uncertainty principle. We comment on the maximum force conjecture, the subtleties involved, as well as the discrepancies with previous results in the literature.

  • 135. Pittelli, Antonio
    et al.
    Preti, Michelangelo
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita).
    Integrable fishnet from γ-deformed N=2 quivers2019Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 798, artikkel-id 134971Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We introduce bi-fermion fishnet theories, a class of models describing integrable sectors of four-dimensional gauge theories with non-maximal supersymmetry. Bi-fermion theories are characterized by a single complex scalar field and two Weyl fermions interacting only via chiral Yukawa couplings. The latter generate oriented Feynman diagrams forming hexagonal lattices, whose fishnet structure signals an underlying integrability that we exploit to compute anomalous dimensions of BMN-vacuum operators. Furthermore, we investigate Lunin-Maldacena deformations of N = 2 superconformal field theories with deformation parameter gamma and prove that bi-fermion models emerge in the limit of large imaginary gamma and vanishing 't Hooft coupling g, with ge(-i/2 gamma) fixed. Finally, we explicitly find non-trivial conformal fixed points and compute the scaling dimensions of operators for any gamma and in presence of double-trace deformations.

  • 136. Reig, Mario
    et al.
    Valle, Jose W. F.
    Vaquera-Araujo, C. A.
    Wilczek, Frank
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. MIT, USA; Shanghai Jiao Tong University, China; Arizona State University, USA.
    A model of comprehensive unification2017Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 774, s. 667-670Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Comprehensive - that is, gauge and family - unification using spinors has many attractive features, but it has been challenged to explain chirality. Here, by combining an orbifold construction with more traditional ideas, we address that difficulty. Our candidate model features three chiral families and leads to an acceptable result for quantitative unification of couplings. A potential target for accelerator and astronomical searches emerges.

  • 137.
    Richter, B.
    et al.
    Kernforschungszentrum, Universität Karlsruche.
    Adiels, L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Manne Siegbahn-laboratoriet.
    Backenstoss, G.
    Institute for Physics, University of Basle.
    Bergström, I.
    Stockholms universitet, Naturvetenskapliga fakulteten, Manne Siegbahn-laboratoriet.
    Blüm, P.
    Kernforschungszentrum, Universität Karlsruche.
    Fransson, K.
    Stockholms universitet, Naturvetenskapliga fakulteten, Manne Siegbahn-laboratoriet.
    Glöckner, M.
    Kernforschungszentrum, Universität Karlsruche.
    Guigas, R.
    Kernforschungszentrum, Universität Karlsruche.
    Hasinoff, M.
    Institute for Physics, University of Basle.
    Kerek, A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Manne Siegbahn-laboratoriet.
    Koch, H.
    Kernforschungszentrum, Universität Karlsruche.
    Köhler, T.
    Kernforschungszentrum, Universität Karlsruche.
    Meyer, M.
    Kernforschungszentrum, Universität Karlsruche.
    Pavlopoulos, P.
    Institute for Physics, University of Basle.
    Poth, H.
    Kernforschungszentrum, Universität Karlsruche.
    Raich, U.
    Kernforschungszentrum, Universität Karlsruche.
    Repond, J.
    Institute for Physics, University of Basle.
    Suffert, M.
    Centre de recherches nucléaries and Université Louis Pasteur, Strabourg.
    Tauscher, L.
    Institute for Physics, University of Basle.
    Tröster, D.
    Institute for Physics, University of Basle.
    Zioutas, K.
    Dept. of Nuclear Physics, Univerity of Tessaloniki.
    New results in the search for narrow states in the p system below threshold1983Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 126, nr 3-4, s. 284-288Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The γ-ray spectrum after p annihilation at rest was measured in two independent high-statistics runs. Both spectra show narrow peaks, corresponding to masses of 1210, 1638, 1694 and 1771 MeV.

  • 138. Schonning, K.
    et al.
    Bargholtz, Christoph
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Bashkanov, M.
    Berlowski, M.
    Bogoslawsky, D.
    Calen, H.
    Clement, H.
    Demiroers, L.
    Ekstrom, C.
    Fransson, K.
    Geren, L.
    Stockholms universitet.
    Gustafsson, L.
    Hoistad, B.
    Ivanov, G.
    Jacewicz, M.
    Jiganov, E.
    Johansson, T.
    Keleta, S.
    Khakimova, O.
    Koch, I.
    Kren, F.
    Kullander, S.
    Kupsc, A.
    Kuzmin, A.
    Lindberg, K.
    Stockholms universitet.
    Marciniewski, P.
    Morosov, B.
    Oelert, W.
    Pauly, C.
    Pettersson, H.
    Petukhov, Y.
    Povtorejko, A.
    Ruber, R. J. M. Y.
    Scobel, W.
    Shafigullin, R.
    Shwartz, B.
    Skorodko, T.
    Sopov, V.
    Stepaniak, J.
    Tegner, P. -E
    Stockholms universitet.
    Engblom, P. Thorngren
    Tikhomirov, V.
    Turowiecki, A.
    Wagner, G. J.
    Wilkin, C.
    Wolke, M.
    Zabierowski, J.
    Zartova, I.
    Stockholms universitet.
    Zlomanczuk, J.
    Polarisation of the omega meson in the pd -> He-3 omega reaction at 1360 and 1450 MeV2008Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 668, nr 4, s. 258-262Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The tensor polarisation of omega mesons produced in the pd -> He-3 omega reaction has been studied at two energies near threshold. The 3 He nuclei were detected in coincidence with the pi(0)pi(+)pi(-) or pi(0)gamma decay products of the omega. in contrast to the case of phi-meson production, the omega mesons are found to be unpolarised. This brings into question the applicability of the Okubo-Zweig-lizuka rule when comparing the production of vector mesons in low energy hadronic reactions.

  • 139. Schonning, K.
    et al.
    Bargholtz, Christoph
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Bashkanov, M.
    Berlowski, M.
    Bogoslawsky, D.
    Calen, H.
    Clement, H.
    Demiroers, L.
    Ekstrom, C.
    Fransson, K.
    Gerén, Linda
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Gustafsson, L.
    Hoistad, B.
    Ivanov, G.
    Jacewicz, M.
    Jiganov, E.
    Johansson, T.
    Keleta, S.
    Khakimova, O.
    Kren, F.
    Kullander, S.
    Kupsc, A.
    Kuzmin, A.
    Lindberg, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Marciniewski, P.
    Morosov, B.
    Oelert, W.
    Pauly, C.
    Petren, H.
    Petukhov, Y.
    Povtorejko, A.
    Scobel, W.
    Shafigullin, R.
    Shwartz, B.
    Skorodko, T.
    Sopov, V.
    Stepaniak, J.
    Tegnér, Per-Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Engblom, Pia Thörngren
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Tikhomirov, V.
    Turowiecki, A.
    Wagner, G. J.
    Wilkin, C.
    Wolke, M.
    Zabierowski, J.
    Zartova, Irina
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Zlomanczuk, J.
    The pd -> He-3 eta pi(0) reaction at T-p=1450 MeV CELSIUS/WASA Collaboration2010Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 685, nr 1, s. 33-37Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The cross section for the pd -> He-3 eta pi(0) reaction has been measured at a beam energy of 1450 MeV using the WASA detector at the CELSIUS storage ring. The He-3 was detected in coincidence with four photons from the decays of the two mesons. The data indicate that the production mechanism involves the formation of the Delta(1232) isobar. Although the beam energy does not allow the full peak of this resonance to be seen, the invariant mass distributions Of all three pairs of final particles are well reproduced by a phase space Monte Carlo simulation weighted with the p-wave factor of the square of the pi(0) momentum in the He-3 pi(0) system.

  • 140. Skorodko, T.
    et al.
    Bashkanov, M.
    Bogoslawsky, D.
    Calen, H.
    Clement, H.
    Doroshkevich, E.
    Demiroers, L.
    Ekstrom, C.
    Fransson, K.
    Gustafsson, L.
    Hoistad, B.
    Ivanov, G.
    Jacewicz, M.
    Jiganov, E.
    Johansson, T.
    Khakimova, O.
    Keleta, S.
    Koch, I.
    Kren, F.
    Kullander, S.
    Kupsc, A.
    Marciniewski, P.
    Meier, R.
    Morosov, B.
    Pauly, C.
    Petren, H.
    Petukhov, Y.
    Povtorejko, A.
    Ruber, R. J. M. Y.
    Schonning, K.
    Scobel, W.
    Shwartz, B.
    Stepaniak, J.
    Thörngren Engblom, Pia
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Tikhomirov, V.
    Wagner, G. J.
    Wolke, M.
    Yamamoto, A.
    Zabierowski, J.
    Zlomanczuk, J.
    Delta Delta excitation in proton-proton induced pi(0)pi(0) production2011Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 695, nr 1-4, s. 115-123Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Exclusive measurements of the pp -> pp pi(0)pi(0) reaction have been performed at CELSIUS/WASA at energies from threshold up to T(p) = 1.3 GeV. Total and differential cross sections have been obtained. Here we concentrate on energies T(p) >= GeV. where the Delta Delta excitation becomes the leading process. No evidence is found for a significant ABC effect beyond that given by the conventional t-channel Delta Delta excitation. This holds also for the double-pionic fusion to the quasibound (2)He. The data are compared to model predictions, which are based on both pi- and rho-exchange. Total and differential cross sections are at variance with these predictions and call for a profound modification of the rho-exchange. A phenomenological modification allowing only a small rho-exchange contribution leads to a quantitative description of the data.

  • 141.
    Visinelli, Luca
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita).
    Baum, Sebastian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita).
    Redondo, Javier
    Freese, Katherine
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita). University of Michigan, USA.
    Wilczek, Frank
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Center for Theoretical Physics, MIT, USA.
    Dilute and dense axion stars2018Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 777, s. 64-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Axion stars are hypothetical objects formed of axions, obtained as localized and coherently oscillating solutions to their classical equation of motion. Depending on the value of the field amplitude at the core vertical bar theta(0)vertical bar vertical bar theta(r = 0)vertical bar, the equilibrium of the system arises from the balance of the kinetic pressure and either self-gravity or axion self-interactions. Starting from a general relativistic framework, we obtain the set of equations describing the configuration of the axion star, which we solve as a function of vertical bar theta(0)vertical bar. For small vertical bar theta(0)vertical bar less than or similar to 1, we reproduce results previously obtained in the literature, and we provide arguments for the stability of such configurations in terms of first principles. We compare qualitative analytical results with a numerical calculation. For large amplitudes vertical bar theta(0)vertical bar greater than or similar to 1, the axion field probes the full non-harmonic QCD chiral potential and the axion star enters the densebranch. Our numerical solutions show that in this latter regime the axions are relativistic, and that one should not use a single frequency approximation, as previously applied in the literature. We employ a multi-harmonic expansion to solve the relativistic equation for the axion field in the star, and demonstrate that higher modes cannot be neglected in the dense regime. We interpret the solutions in the dense regime as pseudo-breathers, and show that the life-time of such configurations is much smaller than any cosmological time scale.

  • 142.
    Widén, Erik
    Stockholms universitet, Nordiska institutet för teoretisk fysik (Nordita). Uppsala University, Sweden.
    Two-point functions of SU(2)-subsector and length-two operators in dCFT2017Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 773, s. 435-439Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider a particular set of two-point functions in the setting of N=4SYM with a defect, dual to the fuzzy-funnel solution for the probe D5-D3-brane system. The two-point functions in focus involve a single trace operator in the SU(2)-subsector of arbitrary length and a length-two operator built out of any scalars. By interpreting the contractions as a spin-chain operator, simple expressions were found for the leading contribution to the two-point functions, mapping them to earlier known formulas for the one-point functions in this setting.

  • 143.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Dependence of the $t\bar{t}$ Production Cross Section on the Transverse Momentum of the Top Quark2010Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 693, nr 5, s. 515-521Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a measurement of the differential cross section for events produced in collisions at as a function of the transverse momentum (pT) of the top quark. The selected events contain a high-pT lepton (), a large imbalance in pT, four or more jets with at least one candidate for a b jet, and correspond to 1 fb−1 of integrated luminosity recorded with the D0 detector. Objects in the event are associated through a constrained kinematic fit to the process. Results from next and next-to-next-to-leading-order perturbative QCD calculations agree with the measured differential cross section. Comparisons are also provided to predictions from Monte Carlo event generators using QCD calculations at different levels of precision.

  • 144.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Determination of the Pole and $\bar{MS}$ Masses of the top quark from the $t\bar{t}$ Cross Section2011Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 703, nr 4, s. 422-427Artikkel i tidsskrift (Fagfellevurdert)
  • 145.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    High Mass Exclusive Diffractive Dijet Production in $p\bar{p}$ Collisions at $\sqrt{s}$ = 1.96 TeV2011Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 705, nr 3, s. 193-199Artikkel i tidsskrift (Fagfellevurdert)
  • 146.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Measurement of Direct Photon Pair Production Cross Sections in $p\bar{p}$ Collisions at $\sqrt{s}=1.96$ TeV2010Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 690, s. 108-117Artikkel i tidsskrift (Fagfellevurdert)
  • 147.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Measurement of Spin Correlation in $t\bar{t}$ Production Using Dilepton Final States2011Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 702, nr 1, s. 16-23Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We measure the correlation between the spin of the top quark and the spin of the anti-top quark in final states produced in collisions at a center of mass energy , where is an electron or muon. The data correspond to an integrated luminosity of 5.4 fb−1 and were collected with the D0 detector at the Fermilab Tevatron collider. The correlation is extracted from the angles of the two leptons in the t and rest frames, yielding a correlation strength , in agreement with the NLO QCD prediction within two standard deviations, but also in agreement with the no correlation hypothesis.

  • 148.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Measurement of the Dijet Invariant Mass Cross Section in $p\bar{p}$ Collisions at $\sqrt{s}=1.96$ TeV2010Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 693, nr 5, s. 531-538Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The inclusive dijet production double differential cross section as a function of the dijet invariant mass and of the largest absolute rapidity of the two jets with the largest transverse momentum in an event is measured in collisions at using 0.7 fb−1 of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. The measurement is performed in six rapidity regions up to a maximum rapidity of 2.4. Next-to-leading order perturbative QCD predictions are found to be in agreement with the data.

  • 149.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Measurement of the Normalized $Z/\gamma^*\to\mu^+\mu^-$ Transverse Momentum Distribution in $p\bar{p}$ Collisions at $\sqrt{s}=1.96$ TeV2010Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 693, nr 5, s. 522-530Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a new measurement of the Z/γ transverse momentum distribution in the range 0–330 GeV, in proton–antiproton collisions at . The measurement uses 0.97 fb−1 of integrated luminosity recorded by the D0 experiment and is the first using the Z/γμ+μ+X channel at this center-of-mass energy. This is also the first measurement of the Z/γ transverse momentum distribution that presents the result at the level of particles entering the detector, minimizing dependence on theoretical models. As any momentum of the Z/γ in the plane transverse to the incoming beams must be balanced by some recoiling system, primarily the result of QCD radiation in the initial state, this variable is an excellent probe of the underlying process. Tests of the predictions of QCD calculations and current event generators show they have varied success in describing the data. Using this measurement as an input to theoretical predictions will allow for a better description of hadron collider data and hence it will increase experimental sensitivity to rare signals.

  • 150.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Measurement of the $t\bar{t}$ Production Cross Section Using Dilepton Events in $p\bar{p}$ Collisions2011Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 704, nr 5, s. 403-410Artikkel i tidsskrift (Fagfellevurdert)
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